Adherence to antidepressants among women and men described with trajectory models: a Swedish longitudinal study

Purpose The purpose of this study are to analyse adherence to antidepressant treatment over 2 years in Sweden among women and men who initiated treatment with citalopram and to identify groups at risk of non-adherence using trajectory models. Methods The study population, including individuals 18–85 years who initiated citalopram use between 1 July 2006 and 30 June 2007, was identified in the Swedish Prescribed Drug Register and followed for 2 years. Adherence was estimated with continuous measure of medication acquisition (CMA) and group-based trajectory modelling, a method which describes adherence patterns over time by estimating trajectories of adherence and the individual’s probability of belonging to a specific trajectory. Results The study population included 54,248 individuals, 64 % women. Mean CMA was 52 % among women and 50 % among men ( p